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  <title>将数组的内部指针倒回一位</title>

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    <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">prev</span> &mdash; <span class="dc-title">将数组的内部指针倒回一位</span></p>

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 <div class="refsect1 description" id="refsect1-function.prev-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <span class="methodname"><strong>prev</strong></span>
    ( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array</code></span>
   )</div>

  <p class="para rdfs-comment">
   将数组的内部指针倒回一位。
  </p>
  <p class="para">
     <span class="function"><strong>prev()</strong></span> 和
     <span class="function"><a href="function.next.html" class="function">next()</a></span> 的行为类似，只除了它将内部指针倒回一位而不是前移一位。
    </p>
   </div>

    <div class="refsect1 parameters" id="refsect1-function.prev-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">array</code></em></dt>

     <dd>

      <p class="para">
       The input array.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.prev-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回数组内部指针指向的前一个单元的值，或当没有更多单元时返回 <strong><code>FALSE</code></strong>。
  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.prev-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4928">
    <p><strong>Example #1 <span class="function"><strong>prev()</strong></span> 及相关函数用法示例</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$transport&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">'foot'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'bike'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'car'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'plane'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$mode&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">current</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">);&nbsp;</span><span style="color: #FF8000">//&nbsp;$mode&nbsp;=&nbsp;'foot';<br /></span><span style="color: #0000BB">$mode&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">next</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">);&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;$mode&nbsp;=&nbsp;'bike';<br /></span><span style="color: #0000BB">$mode&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">next</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">);&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;$mode&nbsp;=&nbsp;'car';<br /></span><span style="color: #0000BB">$mode&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">prev</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">);&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;$mode&nbsp;=&nbsp;'bike';<br /></span><span style="color: #0000BB">$mode&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">end</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;$mode&nbsp;=&nbsp;'plane';<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>

 <div class="refsect1 notes" id="refsect1-function.prev-notes">
  <h3 class="title">注释</h3>
  <div class="warning"><strong class="warning">Warning</strong><p class="simpara">此函数可能返回布尔值
<strong><code>FALSE</code></strong>，但也可能返回等同于 <strong><code>FALSE</code></strong> 的非布尔值。请阅读 <a href="language.types.boolean.html" class="link">布尔类型</a>章节以获取更多信息。应使用
<a href="language.operators.comparison.html" class="link">===
运算符</a>来测试此函数的返回值。</p></div>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <span class="simpara">
    你会无法区分包含 <span class="type"><a href="language.types.boolean.html" class="type boolean">boolean</a></span> <strong><code>FALSE</code></strong> 单元的数组开头。要正确遍历可能含有空单元或者单元值为 0 的数组，参见
       <span class="function"><a href="function.each.html" class="function">each()</a></span> 函数。
   </span>
  </p></blockquote>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.prev-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.current.html" class="function" rel="rdfs-seeAlso">current()</a> - 返回数组中的当前单元</span></li>
    <li class="member"><span class="function"><a href="function.end.html" class="function" rel="rdfs-seeAlso">end()</a> - 将数组的内部指针指向最后一个单元</span></li>
    <li class="member"><span class="function"><a href="function.next.html" class="function" rel="rdfs-seeAlso">next()</a> - 将数组中的内部指针向前移动一位</span></li>
    <li class="member"><span class="function"><a href="function.reset.html" class="function" rel="rdfs-seeAlso">reset()</a> - 将数组的内部指针指向第一个单元</span></li>
    <li class="member"><span class="function"><a href="function.each.html" class="function" rel="rdfs-seeAlso">each()</a> - 返回数组中当前的键／值对并将数组指针向前移动一步</span></li>
   </ul>
  </p>
 </div>

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